Some types of motorcycles have air cooled engines. Notably, motorcycles manufactured by Harley-Davidson Motorcycle Company of Milwaukee, Wis. have large displacement, four stroke, air cooled engines. As is well known, these engines have an oil pump which circulates oil through the engine to lubricate the components thereof and to carry away the accumulated heat of combustion and friction. Under normal operations for a motorcycle of the type described above having a displacement of 80 cubic inches, the oil pump has a discharge pressure of about 12 to 14 PSI. To assure proper circulation and lubrication, it is important that the pressure be maintained. A significant drop in oil pressure can result in damage to engine components.
As is also well known, engines of the type described have replaceable oil filters which are coupled to the engine by suitable means to filter the oil. Typically a mount having a threaded port is presented to threadably mount the filter. The port has an axial bore through which oil from the filter is returned to the engine for re-circulation by the oil pump. The filter has a threaded center bore such that the filter can be threaded and unthreaded from the port. To supply oil to the filter, disposed about the port are one or more openings through which oil from the engine delivered by the oil pump is supplied to the filter. Hence, the oil is pumped through the engine for a lubrication and heat transfer, from the openings and into the filter. Oil passes through the filtering media of the filter and returns to the crank case through the port axial bore.
With continuing reference to the engine of the type described above, the cooling of the engine is carried about by providing fins on the cylinder block. When the motorcycle is moving, forced convection heat transfer occurs to carry away heat.
In stagnant air flow conditions such as when the motorcycle is stopped and running, and particularly in elevated ambient conditions such as in high heat and humidity, the temperature of the oil may rise to such a level that oil pressure is lost. In those circumstances the operator of the motorcycle must turn off the engine or risk damage thereto. The forgoing is true particularly for police motorcycles of the type described above which may be stopped in traffic or involved in slow moving, stop and go traffic. Under these conditions and in the engines of the type described above, insufficient cooling takes place to maintain oil pressure.
In the past, efforts have been made to provide additional oil cooling. For example, in Michl, U.S. Pat. No. 5,244,036, an oil cooler for motorcycle is shown. With reference to FIG. 1 herein, a motorcycle 10, of the type described above, is generically illustrated. The motorcycle 10 has a front wheel assembly 12 including a front wheel 14 and a front fork suspension 16 as is well known in the art. A rear wheel assembly 18 is also provided, both the front wheel and rear wheel assemblies 12 and 18 coupled to a motorcycle frame 20. An engine 22 provides power for the motorcycle 10. Foot pegs 24 provide a resting place for the operators feet. According to this reference, an oil cooler 26 is attached to the motorcycle frame 20 to follow the inverted v-shape pattern of the front portion of the motorcycle frame 20. This oil cooler is supplied with oil from the discharge of an oil filter 28 positioned between the frame 20 and engine 22 and transversely to the direction of travel for the motorcycle 10. The oil circulates through the oil cooler 26 and is returned to the oil reservoir for the motorcycle.
A drawback of prior oil coolers of the type described above, is that their close proximity to the engine does not provide for efficient cooling of the oil. Heat from the engine 22 transferred to the environment, particularly in stagnant conditions when the motorcycles not moving, will increase ambient temperature conditions about the oil cooler 26 effecting the efficiency thereof.
Furthermore, the oil coolers of the type described above provide no other function than as an oil cooler. It is a component which has no other utility than to operate as an oil cooler.
Still further, the location of the oil cooler 26 described, limits the service area available for cooling in that it is coupled to the frame 20. Still further, debris such as dirt and mud thrown up by the front wheel 14 may effect the heat transfer capabilities of the oil cooler.
It is therefore desirable to provide an oil cooler which overcomes these drawbacks.
Unrelated to oil coolers, and further by way of background, it has been known to provide motorcycles with an engine guard, sometimes referred to as a crash bar, mounted to the motorcycle frame to project to either side of the engine. These engine guards protect the engine components should the motorcycle fall to the side and in such event, may also provide the additional benefit of protecting the rider's legs. For Harley-Davidson motorcycles of the type described above, these engine guards may have an inverted U-shape and may be 80 inches long or more with an outside diameter of 1.25 inches. Typically, these engines guards, for purposes of appearances, have a chrome finish.
Heretofore, the art of oil coolers and engine guards have been unrelated.